The presence of immature granulocytes (IG) in peripheral blood is potentially important information which indicates enhanced bone marrow activation. Besides the obvious significance of blasts for the diagnosis of leukaemia, the promyelocyte, myelocyte and metamyelocyte stages of myeloid maturation may indicate systemic inflammatory stress or leukaemic reactions. The determination of immature granulocytes is routinely done by visual microscopy, which requires manual review of each blood sample smear, and is a labor intensive and time consuming task.
Currently, several high end hematology analyzers which utilize optical, fluorescence and impedance measurements to provide automated determination of immature granulocytes of the blood samples. U.S. Pat. No. 5,958,776 (to Sysmex) teaches a lytic reagent and a method of measuring immature granulocytes using light scatter and fluorescence measurements. However, these instruments and their detection systems are expensive, and not suitable for low cost analyzers. Therefore, there is a need for automated and inexpensive determination of immature granulocytes and reduction of manual review rate.
On the other hand, quality control has long been a necessary and routine procedure in clinical hematology. Accuracy in the counting of various types of blood cells is dependent, in part, upon the use of adequate control products and methods of using the control products. With the numerous types of equipment for particle counting now available, quality control by the use of control products is necessary, since the possibility of an instrument malfunctioning is ever present. The traditional method of maintaining a quality control program for automatic particle counting equipment has consisted of providing fresh human blood as a whole blood standard. However, this fresh blood is usable for only one day, therefore, various manufactured control products which have longer product lifetime have been developed.
Commonly used particles in a control product simulate or approximate the types of particles or cells that are intended to undergo analysis. Consequently, these particles have been frequently referred to as analog particles. The analog particles should be selected or designed so that they have certain characteristics that are similar to those of the particles or cells to be analyzed in the instruments. Exemplary characteristics and parameters include similarities in size, volume, surface characteristics, granularity properties, light scattering properties and fluorescence properties.
Various commercial reference control products are now available, which use various processed or fixed human or animal blood cells as analogs of human blood cells. U.S. Pat. No. 4,704,364 (to Carver et al) teaches a hematology control comprising three white blood cell analogs made of fixed animal red blood cells for differential analysis of white blood cells into three subpopulations using DC impedance measurement. U.S. Pat. No. 5,512,485 (to Young et al) teaches a hematology control comprising several white blood cell analogs made of processed and fixed animal red blood cells for differential analysis of white blood cells into five subpopulations using light scatter, radio frequency and DC impedance measurements, commonly referred to as the VCS method.
However, currently no hematology reference control provides an immature granulocyte component, which enables quality control of the immature granulocyte measurement.
Based on the foregoing, there exists a need for a hematology reference control which comprises an immature granulocyte component for quality control of the immature granulocyte measurement.